This invention relates to a color negative silver halide film element in which there are present three yellow dye-forming layers of differing light sensitivity in which the layers and DIR inhibitor couplers contained therein are arranged so as to provide improved color rendition without sacrificing blue density.
Silver halide imaging systems based on chromogenic processing of multistage elements, such as the film-paper system most commonly used for consumer photography, afford significant opportunities to affect the quality, especially as related to color, of the reproduced image. The color quality sub-domains of xe2x80x98colorfulnessxe2x80x99 or saturation and xe2x80x98faithfulnessxe2x80x99 or hue accuracy are influenced by multiple design elements contained within the capture (first stage) media. Included in the list of factors which affect saturation and hue accuracy are (i) the spectral sensitivity of the capture media; (ii) hue characteristics of the individual dyes generated in the capture media upon chromogenic processing and (iii) the level of inter-channel (R, G, B) communications or interlayer interimage effects (IIE). In general, IIE plays a preeminent role in dictating the level of saturation and has a secondary effect on hue accuracy in the optical execution of the color negative imaging chain. Not surprisingly then, most modern color negative films designed for high speed optical printing feature incorporated technologies which provide IIE.
However, one of the more serious detractors associated with aggressive use of IIE technology to enhance color quality is the inability to control, in a site specific manner, the inhibiting impact one layer (causer) has on a desired target layer (receiver) without affecting other (unintended receiver) layers. For example, use of a development inhibitor releasing (DIR) coupler in a red sensitive (causer) element to generate desired IIE on the green sensitive (desired receiver) record, denoted as Rxe2x86x92G, has a parallel and not necessarily desired effect of influencing the response of the blue sensitive (undesired receiver) record, denoted Rxe2x86x92B.
One method for managing this limitation is the use of colored (or xe2x80x98maskingxe2x80x99) couplers to provide the desired site specific color enhancement in the example above. Use of a magenta-colored coupler which provides cyan dye upon chromogenic development, provides a means for generating red channel (causer) generated green channel (receiver) specific IIE by imagewise consumption of the magenta mask in the red sensitized layer. As discussed shortly, however, this strategy is not without serious limitations.
Another tactic used to address desired directed causer/receiver response is to employ xe2x80x98color contaminationxe2x80x99 to compensate for undesired causer/unintended receiver response. In this scenario, a colorless coupler that generates a dye of identical or similar hue to that formed in the unintended receiver, is coated in the causer layer. In principle, by balancing the amount of color contamination coupler coated, a dye scale complementary to the inhibition scale can be used to compensate for the undesired IIE. In the example above, coating a yellow dye forming coupler in the red-sensitized layer could offer relief of the undesired redxe2x86x92blue IIE. However, in practice, this approach is far from satisfactory. At a minimum, some specific proportion of captured red light is redirected toward producing yellow, rather than cyan dye, reducing the efficiency of the red record to record channel specific information.
Equally important to the use of high IIE to enhance color quality is the ability to generate a constant, exposure independent level of targeted cause/desired receiver response. In addition to extending the effective latitude of the capture media, this requirement minimizes saturation and hue fluctuations across the luminance range captured in and common to most uncontrolled lighting situations. Failure to provide constant IIE relationships can affect both hue rendition as well as saturation, particularly if there is a different exposure relationship or sensitivity for the desired and undesired IIE. In many cases, both color contamination and/or colored coupler technology may provide an exposure explicit effect, but vary considerably as exposure varies. It is common for pictures to be over- or under-exposed and it is desired that the color rendition be, nevertheless, accurate.
One of the more difficult IIE relationships necessary for high color quality reproduction of the original scene is bluexe2x86x92green (desired receiver) IIE. In practice, DIR technology in the blue sensitized record operates to generate both the desired interaction as well as bluexe2x86x92red (undesired receiver) IIE. This is particularly troublesome when pursuing very aggressive levels of the desired blue record/green record effect. Similarly, with a traditional layer ordering placement of the blue, green and red sensitive elements with respect to incident exposure, it is not uncommon to observe significant exposure dependencies of both the desired and undesired IIE. This spatial relationship of incoming light having to pass through the blue record before affecting the green sensitive imaging layer also precludes the use of a magenta-colored coupler used in the blue sensitized record to evoke more site specific, desired IIE. Since spectral information utilized by the green record would be unproductively consumed in the blue channel, this strategy, while potentially effective for color management, would lead to an unacceptably high loss in image efficiency. Further, use of xe2x80x98color contaminationxe2x80x99 where a cyan-dye-forming coupler is used to compensate for the yellow dye forming DIR""s traditionally employed in the blue record suffer from several limitations, including both inefficient use of blue channel specific scene information and difficulties in producing an effective profile in the contaminating dye with respect to exposure.
As such, although the art has made strides toward improving the interimage effects caused by the blue layers, further improvements are desired. A problem to be solved is to provide a color negative element exhibiting improved consistency, as a function of exposure level, of Bxe2x86x92R and Bxe2x86x92G interimage effects without sacrificing blue density.
The invention provides a photographic element comprising a support bearing a blue light sensitive record containing at least three layers having different levels of light sensitivity arranged in the order slowest to fastest with the slowest layer closest to the support and the fastest layer closest to the light exposure source, wherein:
a) all of the blue-sensitive layers are closer to the light exposure source than the layers sensitive to any other color,
b) the slowest blue light sensitive layer is at least 1.0 log E slower than the next fastest blue light sensitive layer when measured at a density of 0.15 above Dmin, and contains a cyan dye-forming development inhibitor releasing (DIR) coupler represented by DIR1;
DIR1=Coup1-Time-Inh1
xe2x80x83wherein
Coup1 is a coupler nucleus that releases -Time-Inh1 and forms a cyan dye upon reaction with oxidized developer,
Time is a group that permits -Time-Inh1 to be cleaved from Coup1 and to diffuse within the photographic element during development processing and is thereafter cleaved from Inh1 and
Inh1 is an inhibitor group of high strength capable of inhibiting the development of a silver halide emulsion upon release from Time;
c) all of the blue light sensitive layers other than the slowest blue light sensitive layer independently contain a yellow dye-forming DIR coupler represented by DIR2:
DIR2=Coup2-Inh2
xe2x80x83wherein Coup2 is a coupler nucleus that releases -Inh2 and forms a yellow dye upon reaction with oxidized developer during development processing, and Inh2 is an inhibitor group capable of inhibiting the development of a silver halide emulsion other than one qualifying as a high strength inhibitor.
The invention also provides a process for forming an image in the element of the invention.
Embodiments of the invention provide improved color rendition without sacrificing blue density.